Knowing you're reading this, or just imagining that you are (doing it/so), makes me happy enough.
Can doing it/so be omitted in the sentence above?
Yes, you can omit the repetition of the verb phrase. Omitting words where possible gives velocity to writing. Not repeating things is the essence of many memorable phrases.
"If you’re going through hell, [you should] keep going." -- Winston Churchill
"Ellipsis is the grammatically acceptable exclusion of one or more words from a sentence because their meaning can be easily understood without them."
FROM https://guinlist.wordpress.com/2012/10/01/36-words-left-out-to-avoid-repetition/